1. Field of the Invention
The present invention relates to an observation system, and in particular to an observation system used for observing biological tissue.
2. Description of the Related Art
In endoscope observation, a technique for generating and displaying an observation image in which a mucosal structure and/or a structure of a blood vessel or the like included in biological tissue is emphasized by irradiating the biological tissue with illumination light having a predetermined center wavelength set according to an extinction coefficient with respect to blood is conventionally known.
Specifically, for example, Japanese Patent Application Laid-Open Publication No. 2013-202167 discloses a configuration of generating and displaying an observation image in which surface blood vessels and middle-deep blood vessels of biological tissue are emphasized by irradiating the biological tissue with white light formed of narrowband light, a center wavelength of which is 445 nm, and fluorescence originated from a fluorescent material excited by the narrowband light of 445 nm and narrowband light, the center wavelength of which is 405 nm, as illumination light, when a blood vessel emphasizing observation mode is set in an endoscope system. In addition, Japanese Patent Application Laid-Open Publication No. 2013-202167 discloses that contour emphasizing processing is executed to an image signal including a lot of information on the middle-deep blood vessels when generating the observation image.